The present invention relates generally to mobile irrigation systems and more particularly to center pivot, mobile irrigation systems for watering farm land.
A conventional center pivot, mobile irrigation system includes a plurality of towers spaced-apart and aligned in a row. Each tower comprises a frame having upper and lower portions. At the top or upper portion of each frame is structure for supporting one end of an irrigation pipe section in a horizontal disposition and for coupling that pipe section to another pipe section. The sections of irrigation pipe extend from one tower top to the next, for a total distance up to as much as one half mile. The lower portion of each tower frame is connected to a pair of driven wheels. One end of the irrigation pipe is connected to a water source located adjacent a stationary or immobile pivot tower. Sprinklers are located at spaced intervals along the irrigation pipe.
In operation, the water is turned on, the sprinklers on the pipe begin to sprinkle, and the wheels in each of the mobile towers are driven in a manner which causes the mobile towers, together with the irrigation pipe carried by these towers, to pivot in a circular path about the stationary pivot tower while maintaining their alignment.
Each of the mobile towers in conventional systems is of essentially identical construction, while the stationary pivot tower has a different construction. In one embodiment, the stationary pivot tower is supported atop a concrete slab resting on concrete legs and is anchored in place on the concrete slab with chains, cables or the like, to prevent the pivot tower from moving while the rest of the irrigation system was pivoting about the location of the stationary pivot tower.
The drawbacks in an arrangement of the type discussed above were many. The stationary pivot tower was not susceptible to mass production techniques because only one such construction was required for each system or rig. In comparison, relatively large quantities of mobile towers were used in each system, thereby rendering the mobile towers susceptible to mass production techniques. Moreover, when it came time to move the irrigation system to another field or another portion of the same field, the pivot tower was not as readily transportable as the other towers in the irrigation system, if transportable at all.